code: def _digit_span_to_special_tag(span):
      r"""
  
      :param str span: 需要替换的str
      :return:
      """
      if span[0] == "0" and len(span) > 2:
          return "<NUM>"
      decimal_point_count = (
          0  # one might have more than one decimal pointers
      )
      for idx, char in enumerate(span):
          if char == "." or char == "﹒" or char == "·":
              decimal_point_count += 1
      if (
          span[-1] == "." or span[-1] == "﹒" or span[-1] == "·"
      ):  # last digit being decimal point means this is not a number
          if decimal_point_count == 1:
              return span
          else:
              return "<UNKDGT>"
      if decimal_point_count == 1:
          return "<DEC>"
      elif decimal_point_count > 1:
          return "<UNKDGT>"
      else:
          return "<NUM>"
  
file_path: fastNLP/fastNLP/io/pipe/cws.py
imports: import re
  from itertools import chain
  from .pipe import Pipe
  from .utils import _indexize
  from fastNLP.io.data_bundle import DataBundle
  from fastNLP.io.loader import CWSLoader
label_desc: Use image node_id 5 for calling a global function with example usage: _digit_span_to_special_tag(span) and returns: str, str, span, str, str, str